1. Field of the Invention
The present invention relates to image processing apparatuses and image processing methods for combining an image input from an image input unit and a handwritten image corresponding to content entered by a user. In particular, the present invention relates to an image processing apparatus and an image processing method for combining a handwritten image and a fixed image, which may be a predetermined digital image data, with a background image.
2. Description of the Related Art
In recent years, with the spread and sophistication of apparatuses such as digital cameras, scanners, and printers, there have been proposed techniques in which a digital photo image is not only printed on a recording sheet but is also used in various ways.
Examples of such techniques include a processing technique for allowing handwritten text and drawings to be written in a photo image, and a combining technique for combining digital image data, such as an illustration image, with a photo image. With these techniques, it is possible, for example, to write a message in a photo image taken by a digital camera and create a postcard combined with a decorative frame.
Several methods have been proposed as techniques for combining handwritten text and drawings with a photo image input from an image input apparatus, such as a digital camera or a scanner.
US Patent Application Publication No. 2005/0213174 describes a technique where a handwriting sheet on which an illustration image which serves as an entry sample is combined with a photo image, and is printed. After the user enters text and drawings in an entry area of the printed handwriting sheet, the handwriting sheet is read, and an image corresponding to the handwritten text and drawings (hereinafter referred to as a “handwritten image”) is combined with the photo image.
The above document further describes a method in which the photo image is printed within the entry area of the handwriting sheet, so that the user can see where the entered text and drawings are to be positioned in the photo image. To read the handwriting sheet generated by this method, it may be necessary to distinguish the handwritten image from a printed background image so as to extract the handwritten text and drawings. Therefore, the background image is printed lightly and a threshold value of luminance is set for reading the handwriting sheet. Then, in the read image, a portion having luminance lower than the threshold value is determined to be a portion handwritten by the user.
As a method for combining an illustration image, Japanese Patent Laid-Open No. 2000-295565 describes a method in which a frame image recorded in a recording medium, such as a memory card, is read out and combined with a photo image to decorate it, which is then printed.
With the known techniques described above, an illustration image may be combined with a photo image to form a composite image, and a handwritten image entered by the user may be combined with the composite image. To allow the user to enter a handwritten image while checking the resulting composite image, it is possible to print, using the above-described method, an illustration image and a lightly-printed background image (hereinafter referred to as a “reference image”) in an entry area of a handwriting sheet.
To read this handwriting sheet, an image of an area where the illustration image is printed may need to be extracted separately from the reference image, as in the case of the handwritten image. However, if a portion of the illustration image has a luminance higher than a threshold value, an image of this portion may not be extracted during reading. This may cause a problem in that the resulting printed illustration may be partially missing. Therefore, the illustration image may need to have luminance lower than the set threshold value. This means that high-luminance colors typically cannot be used for illustration images.